Wire cropping and forming tools and to a method of utilising the same

ABSTRACT

A wire cropping tool which may be used for cropping wires to any required length after insertion of the wires through holes in a printed circuit board, consist of fixed and movable blades relatively movable upon actuation of a piston member reciprocable within a housing, the fixed blade having at the nose, a notch providing a shearing edge extending substantially normal to the plane of the fixed blade and an extension adjacent the shearing edge extending outwardly with respect thereto, and the movable blade being so fulcrummed with respect to the fixed blade as to allow a lug on the extremity of the movable blade and provided with a shearing edge to move through a curved path and substantially normal to the fixed blade thereby providing a positive cropping action. After cropping, the wires may be bent through any required angle and the construction of the tool allows the blades to be inserted into a stack of wires from above, i.e., with the pivotal axis of the blades substantially normal to the axis of the wires, such as to crop the wires thereby avoiding the difficulties of cropping wires by means of a tool inserted laterally or at an angle to the wires as heretofore.

United States Patent [191 Rose [ 1 Oct. 29, 1974 [75] lnventor: Edwin James Rose, Fareham,

England [73] Assignee: Elite Engineering Limited, Fareham,

England [22] Filed: Dec. 13, 1971 [21] Appl. No.: 207,608

Related US. Application Data [62] Division of Ser. No. 814,409, April 8, 1969,

abandoned.

[30] Foreign Application Priority Data [58] Field of Search 29/203 B, 203 H; 30/134, 30/135, 257; 7/5.4, 5.6, 14.1; 140/1, 106, 123; 72/332, 335, 409

2/1969 l/l97l Romeo 29/203 B Pawloski 140/123 Primary Examiner-Charles W. Lanham Assistant Examiner-E. M. Combs Attorney, Agent, or Firm-Holman & Stern [5 7 ABSTRACT A wire cropping tool which may be used for cropping wires to any required length after insertion of the wires through holes in a printed circuit board, consist of fixed and movable blades relatively movable upon actuation of a piston member reciprocable within a housing, the fixed blade having at the nose, a notch providing a shearing edge extending substantially normal to the plane of the fixed blade and an extension adjacent the shearing edge extending outwardly with respect thereto, and the movable blade being so fulcrummed with respect to the fixed blade as to allow a lug on the extremity of the movable blade and provided with a shearing edge to move through a curved path and substantially normal to the fixed blade thereby providing a positive cropping action. After cropping, the wires may be bent through any required angle and the construction of the tool allows the blades to be .inserted into a stack of wires from above, i.e., with the pivotal axis of the blades substantially normal to the axis of the wires, such as to crop the wires thereby avoiding the difficulties of cropping wires by means of a tool inserted laterally or at an angle to the wires as heretofore.

1 Claim, 9 Drawing Figures [56] References Cited UNITED STATES PATENTS 2,228,635 l/l94l Magennis 30/249 2,783,483 3/1957 Seher 7/5.6 2,800,960 7/1957 Cutler 7/5.4 2,893,010 7/1959 Stuhre 29/203 B 3,262,201 7/1966 Docken 30/240 SHEET 10F 4 PATENTEDncI 29 m4 INVENAIO 0M/Af 73, 5

' ATTORNEYS! 1 WIRE CROPPING AND FORMING TOOLS AND TO A METHOD OF UTILISING THE SAME This is a divisional of application Ser. No. 8l4,409 filed Apr. 8, 1969 now abandoned.

This invention relates to wire cropping tools and to a method of utilising such tools, and particularly, but not exclusively, to a tool for cropping and forming the wires or leads used for connecting electrical circuit components such as resistors, capacitors, transistors and the like, to printed circuit boards.

I-Ieretofore, a wire cropping and forming tool having a reciprocatory blade, slidable within a tubular bore, has been used in order to crop and form the wires or leads of such components after insertion of the wires in apertures formed in the printed circuit board, and prior to the sealing or soldering of the wires to the current conducting tracks of the board, and it has been necessary for a printed circuit board assembler to hold the tool at an angle to the plane of the board, such that the longitudinal axis of the blade is substantially normal to the axis of the wires to be cropped, or arranged at an acute angle to the plane of the board, in order to effectively crop the wires and bend the wires at an angle with respect to the plane of the board in accordance with predetermined requirements. When a large number of components are required to bemounted on one or both surfaces of a printed circuit board by means of wires projecting through apertures formed in the board and to be connected to the tracks of printed circuits formed on the opposite surface of the board, it is difficult to insert the nose of the tool between the wires projecting through the apertures in the board, when the wires are densely packed.

Accordingly, it is an object of the present invention to provide a method of cropping wires which enables a wire cropping and forming tool to be inserted without difficulty between adjacent ones of a plurality of densely packed wires.

A further object of the present invention isto provide a wire cropping and fomiing tool capable of being inserted between adjacent ones of a plurality of densely packed wires, such as to effectively crop the wires to a predetermined length and bend the wires through a predetermined angle.

According to one aspect of the present invention applicable to a method of cropping wires without forming, there is provided a method of cropping individual wires from a plurality thereof wherein a wire cropping tool having a pair of relatively movable blades, at least one of which is pivoted, is inserted between the wires with the pivotal axis of the said at least one blade substantially normal to the axis of the wires such as to effectively crop the wires to any predetermined required length.

According to a further aspect of the present invention there is provided a method of cropping and forming individual wires from a plurality thereof wherein a wire cropping tool having a pair of relatively movable blades at least one of which is pivoted is inserted between the wires with the pivotal axis of the blade said at least one blade substantially normal to the axis of the wires such as to effectively crop the wires to any predetermined required length, and including the step of bending the wires after cropping through a predetermined angle.

According to a still further aspect of the invention there is provided a wire cropping tool having a pair of relatively movable blades, one of which is pivoted on the other and arranged such as to crop any one of a plurality of wires when the noses of the blades are inserted between the wires with the pivotal axis of the said one blade substantially normal to the axis of the wires.

In a preferred embodiment of the invention, applicable to a method of cropping and forming wires, the wire cropping and forming tool is used for cropping the wires of circuit components such as transistors, resistors or capacitors to be mounted on one or both surfaces of a printed circuit board. One or both planar surfaces of the board is or are etched and treated to form the printed circuits required and the board is provided with a plurality of apertures through which wires or leads for the components are intended to project. At least some of the components, which are required to be mounted on the opposite surface of the board remote from the printed circuit surface applicable thereto, are each provided with two or more wires or leads which if necessary are formed to a suitable configuration with the wires parallel. The multi-wire components are assembled on the board by passing the ends of the wires through spaced apertures in the board, and in order to firmly locate the component in position, and to connect the components in the printed circuit, the ends of the wires projecting through the apertures are cropped at a predetermined distance from the board e.g., .080 inch and formed by bending the wire in any required direction e.g., along a narrow track of electrically conductive material e.g., copper and at any required angle with respect to the plane of the board such as to retain the component in position prior to and during a subsequent soldering operation.

The invention will now be described by way of example only with particular reference to the accompanying drawings wherein:

FIG. I is a side, part sectional elevation of a wire cropping and forming tool according to the invention;

FIGS. 2a and 2b are plan and elevational views of the fixed blade of the tool of FIG. 1;

FIGS. 3a and 3b are plan and elevational views respectively of the movable blade of the tool of FIG. 1, and

FIGS. 4a, 4b and 4c are diagrammatic views illustrating the manner in which the noses of the blade members cooperate to cut and bend the wire.

Referring to FIGS. 1, 2a, 2b and 3a, 3b, the wire cropping and forming tool comprises a cylindrical housing or handle portion 1 having a tubular bore containing a piston or plunger 2; the bore being arranged to be connected by a suitable threaded connection (not shown) to a compressed air supply line. When the compressed air supply is turned on, the piston is arranged to be actuated in an axial direction along the bore such as to project into a chamber 3 formed in an extension of the housing or handle of the tool. A fixed blade member 4 is mounted by means of screws 5 on the inner wall surface of chamber 3. The screws 5 pass through holes 5a in the fixed blade 4 and are countersunk. The major portion of the blade projects from the chamber 3 and extends substantially normal to the axis of the tool. A further blade 6 is pivotally mounted at 6a on the fixed blade 4 and has the root end 7 thereof located in the path of the piston or plunger 2 and the nose portion 8 thereof lying closely adjacent the nose portion 9 of the fixed blade 4. A lug or projection 10 on the fixed blade 4 allows a V-shaped spring 11 to be located between the end of chamber 3 remote from the piston 2 and the leading edge of the pivoted blade'6 such as to bias the latter into engagement with the end of the piston 2.

The chamber 3 is arranged to be closed by a cylindrical sleeve 12 formed with a slot (not shown) extending throughout substantially the whole of its length, the ends of the fixed and movable blades 4, 6, extending from the chamber 3 being located within the slot and the cylindrical sleeve 12 serving as a guard and to retain spring 11 in assembled relationship. The sleeve is arranged to be retained in position on the extension of the cylindrical housing by means of a screw 13 passing through tapped holes in the sleeve and extension.

The fixed blade 4 has a tapered nose portion which at its end has a notch or cut-out providing a shearing edge 14 extending substantially normal to the plane of the blade and an extension 14 adjacent the shearing edge which extends outwardly with respect to the shearing edge. The shearing edge 14 and extension 14 are adjacent to the pivoted blade 6 and the latter has a turned over portion or lug 15 extending substantially normal to the plane of the blade having a shearing edge 15' and arranged to co-operate with the shearing edge 14 and the extension 14 of the fixed blade 4 to effect the cropping and forming of wires as will be hereinafter described.

Upon axial movement of the piston 2, the root 7 of the pivoted blade 6 moves against the bias of the spring 11 and causes the blade 6 to be fulcrummed about the pivot 60. The lug 15 on the nose 8 of the pivoted blade 6 moves into close proximity with the portion 14 of the fixed blade 4 and any wire located between the tips of the blades 4 and 6 would be cropped by the shearing edges 14' and 15'. The pivoted blade 6 is fulcrummed such that the lug 15 on the extremity thereof moves substantially normal to the tip of the fixed blade 4 and through a curved path thereby providing an extremely positive cropping action initially and allowing the wire to be formed over at any required angle to the plane of the printed circuit board.

The wire is cropped initially to any required length e.g., .080 inch and in the same movement, the wire is formed over at any required angle such as to lie, for example along a narrow track of electrically conductive material such as copper on the surface of the board. The forming operation retains the component in position on the board prior to and during a subsequent soldering operation.

It will be appreciated that a wire cropping and forming tool of the above construction is capable of being used by a printed circuit board assembler from a position above the board and any wires projecting therethrough. The assembler may hold the tool with the handle or housing arranged substantially parallel to the plane of the board and insert the blades between the upstanding wires on the board i.e., with the blades substantially parallel to the wires and with the pivotal axis of the blades substantially normal thereto. Thus, despite the fact that the wires may be very close together, the constructional features of the tool allow the blades to be inserted from above whereas great difiiculty would be experienced in cropping and forming the wires by means of a tool inserted laterally or at a relatively small angle with respect to the plane of the board.

ltwill further be appreciated that the invention has been described by way of example only and is in no way limited to the particular constructional features described. The blades of the tool may be of any shape such as to allow them to be used in the manner specified and the pivoted blade may be actuated by any suitable means other than the piston specified and other than by means of compressed air. Instead of having the handle arranged substantially at right angles to the longitudinal axes of the blades, it will be appreciated that the handle may be arranged in substantial alignment with'the longitudinal axes of the blades.

I claim:

l. A wire cropping and forming tool including a fixed tapered blade member, a movable tapered blade member pivotally mounted to the fixed blade member for movement relative thereto, each blade member having upper and lower surfaces and a nose, with the lower surface of the movable blade member being in engagement with the upper surface of the fixed blade member, the fixed blade member having at its nose a notch defined by a shearing edge extending from the upper surface substantially normal thereto and terminating short of the lower surface and an extension surface extending outwardly from said shearing edge substantially normal thereto between the shearing edge and the lower surface, the movable blade member having at the nose thereof a lug extending from the lower surface substantially normal to the lower surface, the lug having a shearing edge extending from the upper surface substantially normal thereto, the arrangement being such that with a wire inserted between the noses and upon movement of the movable blade member, the shearing edge of the lug coacts with the shearing edge of the fixed blade member to crop the wire and upon continued movement, the lug bends the wire. 

1. A wire cropping and forming tool including a fixed tapered blade member, a movable tapered blade member pivotally mounted to the fixed blade member for movement relative thereto, each blade member having upper and lower surfaces and a nose, with the lower surface of the movable blade member being in engagement with the upper surface of the fixed blade member, the fixed blade member having at its nose a notch defined by a shearing edge extending from the upper surface substantially normal thereto and terminating short of the lower surface and an extension surface extending outwardly from said shearing edge substantially normal thereto between the shearing edge and the lower surface, the movable blade member having at the nose thereof a lug extending from the lower surface substantially normal to the lower surface, the lug having a shearing edge extending from the upper surface substantially normal thereto, the arrangement being such that with a wire inserted between the noses and upon movement of the movable blade member, the shearing edge of the lug coacts with the shearing edge of the fixed blade member to crop the wire and upon continued movement, the lug bends the wire. 